1. No. Minor Children can not sign any legal document,
2. Wife also can not sign for her minor children for transferring their shares of property,
3. District Judge is the custodian of all the properties of children located at his/her jurisdiction,
4. For dealing with the share of the property of the minor children, the approval of the local District Judge is required and in that case the District Judge shall have to be convinced that the said sell of minor's share of the property is for their welfare only and not for any other purpose,
5. So as of now you are the owner bof the share of your Aunty only.